Search Error

I get this error when using the search…

Warning: Cannot modify header information – headers already sent by (output started at /home/content/a2pewpnas01_data03/08/3968208/html/wp-content/themes/AskBug-3-child-theme-01/header.php:12) in /home/content/a2pewpnas01_data03/08/3968208/html/wp-includes/pluggable.php on line 1179